分页语句 where 条件列和Order by 列 引导列的问题

SQL> select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST'));


PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SQL_ID	599jjhj1rar9u, child number 0
-------------------------------------
select rownum - 1 as xuhao, ggbt, czsj, fj, id	 from (select  *
   from mbank.t_ises_gg t	   where t.status = '1' 	   and
to_date(t.zzrq, 'YYYY-MM-DD') >=		to_date('20150310',
'YYYY-MM-DD')	       order by czsj desc)  where rownum <= 4

Plan hash value: 747778291

--------------------------------------------------------------------------------------------------------------------------------------
| Id  | Operation		       | Name		| Starts | E-Rows | A-Rows |   A-Time	| Buffers |  OMem |  1Mem | Used-Mem |
--------------------------------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT	       |		|      1 |	  |	 4 |00:00:00.01 |      10 |	  |	  |	     |
|*  1 |  COUNT STOPKEY		       |		|      1 |	  |	 4 |00:00:00.01 |      10 |	  |	  |	     |
|   2 |   VIEW			       |		|      1 |	2 |	 4 |00:00:00.01 |      10 |	  |	  |	     |
|*  3 |    SORT ORDER BY STOPKEY       |		|      1 |	2 |	 4 |00:00:00.01 |      10 |  4096 |  4096 | 4096  (0)|
|   4 |     TABLE ACCESS BY INDEX ROWID| T_ISES_GG	|      1 |	2 |	29 |00:00:00.01 |      10 |	  |	  |	     |
|*  5 |      INDEX RANGE SCAN	       | T_ISES_GG_IDX1 |      1 |	1 |	29 |00:00:00.01 |	1 |	  |	  |	     |
--------------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter(ROWNUM<=4)
   3 - filter(ROWNUM<=4)
   5 - access("T"."SYS_NC00019$">=TO_DATE('20150310','YYYY-MM-DD') AND "T"."STATUS"='1' AND "T"."SYS_NC00019$" IS NOT NULL)
       filter("T"."STATUS"='1')


28 rows selected.



 create index mbank.t_ises_gg_idx1 on mbank.t_ises_gg(to_date(zzrq, 'YYYY-MM-DD'),czsj,status)


此时创建的索引顺序为,where 条件列再前




创建如下索引:
 create index mbank.t_ises_gg_idx1 on mbank.t_ises_gg(czsj,to_date(zzrq, 'YYYY-MM-DD'),status);

order by 列在前


SQL> select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST'));


PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SQL_ID	599jjhj1rar9u, child number 0
-------------------------------------
select rownum - 1 as xuhao, ggbt, czsj, fj, id	 from (select  *
   from mbank.t_ises_gg t	   where t.status = '1' 	   and
to_date(t.zzrq, 'YYYY-MM-DD') >=		to_date('20150310',
'YYYY-MM-DD')	       order by czsj desc)  where rownum <= 4

Plan hash value: 3991473710

----------------------------------------------------------------------------------------------------------
| Id  | Operation		      | Name	       | Starts | E-Rows | A-Rows |   A-Time   | Buffers |
----------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT	      | 	       |      1 |	 |	4 |00:00:00.01 |       4 |
|*  1 |  COUNT STOPKEY		      | 	       |      1 |	 |	4 |00:00:00.01 |       4 |
|   2 |   VIEW			      | 	       |      1 |      2 |	4 |00:00:00.01 |       4 |
|   3 |    TABLE ACCESS BY INDEX ROWID| T_ISES_GG      |      1 |      2 |	4 |00:00:00.01 |       4 |
|*  4 |     INDEX FULL SCAN DESCENDING| T_ISES_GG_IDX1 |      1 |      1 |	4 |00:00:00.01 |       2 |
----------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter(ROWNUM<=4)
   4 - access("T"."STATUS"='1' AND "T"."SYS_NC00019$">=TO_DATE('20150310','YYYY-MM-DD'))
       filter(("T"."STATUS"='1' AND "T"."SYS_NC00019$">=TO_DATE('20150310','YYYY-MM-DD')))


26 rows selected.

此时只访问了4条记录。

验证了 分页SQL 引导列不一定是where 条件列